1. Field of the Invention
This invention relates to telephone answering devices. In particular, it relates to the charging of telephone calls directed to an answering device utilized to automatically answer incoming telephone calls intended for a called telephone station.
2. Description of the Prior Art
Telephone answering devices provided for use with telephone stations function to recognize and automatically acknowledge telephone calls generated by telephone calling subscribers. Such answering devices are arranged to automatically answer incoming telephone calls and to transmit prerecorded messages to the calling subscribers. A telephone answering device may also be arranged to transmit a prerecorded message to a calling subscriber informing the subscriber that the answering device is arranged to record messages should the calling subscriber desire to leave a message for the called subscriber. Messages transmitted by the calling subscribers are recorded by the telephone answering device for subsequent reproduction by the called subscriber and restored to a normal or idle state after recording the transmitted messages by releasing the involved telephone central office connections. Telephone answering devices presently available for use inform calling subscribers of a wide variety of matters, such as conditions which exist in a telephone switching network, prerecorded called subscriber messages, and of the unavailability of called subscribers.
One type of answering device employed for use in the telephone switching network is arranged to answer telephone calls that cannot be completed to a called telephone station by informing a calling subscriber of conditions within the telephone switching network which prevent the completion of calls. This type of answering device is sometimes referred to as an announcement machine and is generally associated with a telephone central office trunk circuit that disconnects a calling subscriber from the announcement machine following the transmission of a prerecorded message. Since the calling subscriber did not complete the call as intended, announcement machines are arranged to answer incoming calls on a nonmessage charge basis.
Another type of answering device is employed for use in answering incoming calls directed to a called subscriber telephone station and to transmit a prerecorded message to the calling subscriber. Such answering devices are generally associated with a telephone line circuit and are arranged to record messages transmitted by the calling subscriber that are intended for a called subscriber. These answering devices answer incoming calls on a message charge basis and usually provide a medium for enabling a calling subscriber to leave a message for the called subscriber.
A calling subscriber may react unfavorably when charged for a telephone call directed to a called telephone station that is automatically answered by a telephone answering device. If the calling subscriber makes frequent calls to telephone stations equipped with answering devices, particularly to telephone stations located in distant cities, the subscriber could become irate at frequent message charges incurred when the subscriber intended to confer with called subscribers but instead received nothing more than prerecorded messages notifying the calling subscriber that the called subscribers are not available. When a calling subscriber responds to a prerecorded message by transmitting a message to be recorded, the calling subscriber receives a service for his benefit and should logically be assessed a message charge for the use of the telephone facilities. It is highly desirable that an answering device be provided that satisfies both the calling subscriber and telephone company requirements for assessing message charges for calls directed to answering devices. However, presently available answering devices appear to only answer incoming telephone calls on either a message charge or nonmessage charge basis.
Accordingly, a need exists in the art for an automatic telephone call answering device arranged for controlling the message charge intervals of an incoming telephone call. A need also exists for a telephone call answering device arranged to establish an interval following the answering of an incoming call during which calling subscribers may disconnect without incurring message charges.